If there were a single event of the 20th century that we could magically undo, would it not be the war of 1914-1918? It led to some 20 million military and civilian deaths, the rise of Nazism, the Russian Revolution, and another even more destructive world war. On the centennial of WWI, the “War to End All Wars,” eminent historian Adam Hochschild revisits that pivotal epoch. His 2011 book To End All Wars: A Story of Loyalty and Rebellion, 1914-1918 reminds us of the shock provoked by the mass slaughter of the First World War and stands as a rebuke to the callous acceptance of mass violence and war perpetuated up to the present moment by the U.S. government.